Pumping plant for liquefied gas



H. BONNAUD April 12, 1955 PUMPING PLANT FOR LIQUEFIED GAS Filed Jan. 2, 1952 INVENTOR ///VE/ BOA/M4110.

ATTORNEY United States Patent PUNIPING PLANT FOR LIQUEFIED GAS Henri Bonnaud, Viroflay, France, assignor to LAir Liquide, Societe Anonyme pour lEtude et lExploitation des Procedes Georges Claude Application January 2, 1952, Serial No. 264,398

2 Claims. (Cl. 62-1) This invention relates to a pumping plant for liquefied gas, and, more particularly, to plants for the distribution of liquid oxygen which comprise a tank, a high pressure pump outside this tank but grouped therewith into one assembly heat insulated and built so as to reduce to a minimum oxygen losses during the handlings and pump- In such plants, the pump is immersed in liquid oxygen, in a tight tub which is in communication, at its lower portion, with the outlet of the liquid oxygen from the tank and, at its upper portion, with the gas phase of this same tank. The conduit which connects the gas phase in the tank with the tub starts from a point on the latter, located at a level substantially lower than the highest point of the tight capacity of said tub, but higher than the mean level of the suction ports of the pump, so as to keep a gas buffer at the upper portion of the tub, above a substantially constant level of liquid oxygen, without ever uncovering said suction ports.

The invention has for its object to facilitate the handling during the utilisation of the pumping plants of the above described type and to this end, it consists in providing on the conduits which connect the tub respectively with the liquid outlet from the tank and with the gas phase in said tank, check valves, on the one hand, and valves for communication with the outside, on the other hand, so as to allow, at will, to return the liquid from the tub to the tank, to coolthe tub and pump by a circulation of gaseous oxygen from the tank or to blow a hot gas for defrosting the pump.

The single figure of the accompanying drawing is a diagrammatic section of a plant for pumping liquid oxygen according to the invention.

Referring to said drawing, the plant comprises, in a single unit designed for instance for being secured on the platform of an automobile vehicle or trailer, the usual liquid oxygen tank 1, assumed to be spherical and the tight tub 2 with the pump 3, said unit being carefully heat insulated. The tight tub is in communication with the liquid outlet 4 from the tank and with the gas phase 5 therein, and it is entirely located below the horizontal plane going through the outlet 4 of the liquid, at the lowest point of the tank. The tub 2 is in communication with the gas phase 5 in the tank 1 through a conduit 6 which connects with the tank 1, in principle at the highest point thereof, and with the tub at an intermediate point 7, situated below the outlet point 4, and above the average level of the suction ports 8 of the pump. The assembly of the pump body and the delivery conduit 9 for liquid oxygen is supported by a base 10, suitably heat insulated, which constitutes a sealed upper cover for the tub 2 and is secured thereon so as to allow an easy dismantling. On the diagrammatic figure, the control means for the piston have not been represented, as they may be of any type whatsoever.

In the initial position, the valves 11 and 12, provided respectively on the conduits 6 and 13 being open, liquid oxygen flows into the previously cooled tub, as will be explained further on. This flow is due to gravity and is independent of the value of the pressure of the gas phase in the tank 1. The liquid remains automatically, in the tub, at a level determined by the position of point 7 and the upper portion of the sealed capacity of the tub forms a gas buffer which discharges into the gas phase of the tank, possibly forcing back a little liquid into said tank through the conduit 6. It may be said, that everything else being equal, the pressure at the entrance to the suction ports 8 of the pump varies only gradually with the lowering of the liquid level in the tank.

According to the invention, there are provided, in addition to the valves 11 and. 12 on the conduits 6 and 13, valves 14 and 15 for putting these conduits in communication with the outside at points respectively 10- cated between the valves 11 and 12 and the tub 2, point 16 on the conduit 13 being preferably the lowest point thereof.

These valves allow the following operations:

Before the pump is started, the valves 12 and 14 being closed, the valves 11 and 15 may be opened to circulate the gaseous oxygen from the tank 1 in the tub 2 and obtain an advantageous preliminary cooling of said tub and of the pump 3.

Before starting the pump, valves 14 and 15 are closed and valves 11 and 12 are opened, which allows the filling of the tub 2 with liquid oxygen up to the level of point 7, as explained above.

At the end of a pumping operation, or for dismantling the pump, the liquid contained in the tub 2 may be sent to the tank 1. To this effect, the valves 11, 14 and 15 are closed, and the valve 12 is opened. The pressure increase in the gas phase at the upper portion of the tub 2 forces the liquid into the tank 1 through the conduit 13. This forcing may be accelerated by blowing a gas through the open valve 14. A level indicator 17 makes it possible to note the end of this forcing back.

The valves 11 and 12 being closed and the valves 14 and 15 open, a dry and hot gas may be blown through one of these two latter valves, preferably valve 14, for warming up the tub and defrosting the pump, for instance, if necessary.

In addition to that normally provided on the tank 1, a safety valve S may also be provided on the conduit 18 between the valve 14 and the tub 2.

What I claim is:

1. In a plant for pumping a liquefied gas from a tank, in which a pump has its body provided with suction ports flooded in liquefied gas fed by gravity from the tank to a closed tub surrounding said pump body, a pipe and cock system comprising a first pipe connecting the lowest point of the tank with the lowest point of the tub, a first cock provided on said first pipe, a branch pipe extending from the first pipe, a second cock provided on said branch pipe, a second pipe connecting the gaseous phase of the tank with the tub at a point at a level situated between the pump suction ports and the top of the tub, a third cock provided on said second pipe, a third pipe extending from said second pipe and adapted to be connected with a source of fluid, and a fourth cock provided on said third pipe, the first and third cocks being open and the second and fourth cocks closed when pumping liquefied gas, the first cock being open and the other cocks closed for returning to the tank the liquefied gas remaining in the tub, and the fourth and the second cocks being open and the other cocks closed for allowing to circulate a heating fluid through the tub.

2. In a plant for pumping a liquefied gas from a tank, in which a pump has its body provided with suction ports flooded in liquefied gas fed by gravity from the tank to a closed tub surrounding said pump body, a pipe and cock system comprising first conduit means having connections with the lowest point of the tank, with the lowest point of the tub and with a source of fluid, a first cock means controlling said first conduit means between the connection with the tank and the connection with the source of fluid, second cock means controlling the first conduit means between the source of fluid and the tub, a second conduit means having a connection with the gaseous phase of the tank, with the tub at a point at a level situated between the pump suction ports and the top of the tub, and with a source of fluid, third cock means controlling said second conduit means between the top of the tank and the source of fluid, and fourth cock means controlling the second conduit means between the source of fluid and the tub, the first and third cock means being open and the second and fourth cock means closed when pumping liquefied gas, the first cock means open and the other cock means closed for returning to the tank the liquefied gas remaining in the tub, and the fourth and the second cock means being open andthe other cock means closed for allowing cir- 5 culation of a heating fluid through the tub.

References Cited in the file of this patent UNITED STATES PATENTS 

1. IN A PLANT FOR PUMPING A LIQUEFIED GAS FROM A TANK, IN WHICH A PUMP HAS ITS BODY PROVIDED WITH SUCTION PORTS FLOODED IN LIQUEFIED GAS FED GRAVITY FROM THE TANK TO A CLOSED TUB SURROUNDING SAID PUMP BODY, A PIPE AND COCK SYSTEM COMPRISING A FIRST PIPE CONNECTING THE LOWEST POINT OF THE TANK WITH THE LOWEST POINT OF THE TUB, A FIRST COCK PROVIDED ON SAID FIRST PIPE, A BRANCH PIPE EXTENDING FROM THE FIRST PIPE, A SECOND COCK PROVIDED ON SAID BRANCH PIPE, A SECOND PIPE CONNECTING THE GASEOUS PHASE OF THE TANK WITH THE TUB AT A POINT AT A LEVEL SITUATED BETWEEN THE PUMP SUCTION PORTS AND THE TOP OF THE TUB, A THIRD COCK ROVIDED ON SAID SECOND PIPE, A THIRD PIPE EXTENDING FROM SAID SECOND PIPE AND ADAPTED TO BE CONNECTED WITH A SOURCE OF FLUID, AND A FOURTH COCK PROVIDED ON SAID THIRD PIPE, THE FIRST AND THIRD COCKS BEING OPEN AND THE SECOND AND FOURTH COCKS CLOSED WHEN PUMPING LIQUEFIED GAS, THE FIRST COCK BEING OPEN AND THE OTHER COCKS CLOSED FOR RETURNING TO THE TANK THE LIQUEFIED GAS REMAINING IN THE TUB, AND THE FOURTH AND THE SECOND COCKS BEING OPEN AND THE OTHER COCKS CLOSED FOR ALLOWING TO CIRCULATE A HEATING FLUID THROUGH THE TUB. 